will changing IPs affect SE rankings?
 

I am migrating a few sites from one server to another. I will have to change the IPs of the sites to do this to avoid downtime. Will changing IPs affect my sites' SE rankings?

(If anyone knows how to migrate and keep the same IP without any downtime, let me know. As far as I know it is impossible, but I have limited knowledge in this area.)

it won't affect the ranking since SEs don't store the IP address, but the domain name.

I am not to sure about that. I remember hearing that a bunch of domains all on the same IP are sometimes put down by SEs as they do not have an IP all to themselves. Is this true?

Not true,unless you have some 100s domains in a single IP crosslinked. I recommend to webmasters have a separate IP for each domain, but again if you have 3-4 domains in a single IP is not a problem. The main concern about the IP was that google can spider up to certain # of pages that exist on a single IP, so having many domains (and probably pages) you limit the amount of your spidered pages. Another mistake that is commited often is the crosslinking of the domains. This is for sure won't help you a lot to achive a top spot on google and in case you have all of the domains under the same IP it will be easier to get ignored by google.

This means that SE do store IPs and not just domain names. Also, I will be crosslinking all my domains, so you suggest getting seperate IPs for each? $2/month/domain for me, so it is not that expensive.

As far as I know Googlebot remembers IPs to speed up stuff and it takes him a up to one month to refresh IP info when you switch servers. But I can't tell if it will affect ranking, maybe it will only make problems if Googlebot tried to refresh his cache during the month.
XM

They don't store IPs as critical data meaning that the IP is just a locator and if you change the domain it won't affect the listing. Don't cross link your domains,at least not in the traditional way, it will get you nowhere. And since the cost puting them on separate is affordable,it's preferable to do it.

and to be more specific, google monitors linking back and gives a degree of spam depending the link, having them all in one IP it will be very bad. If you don't cross-link them like crazy you won't have problem even if they are on the same IP.

The webmasters at SE forums will tell you different things, but this doesnt mean they are valid.

Can you please explain what you mean by "traditional way"? I just want to make a links page on all my sites that link to all my other sites. Is this what you mean?

Let's say you have the domain A and you link to domains B,C,D,E,F and G
Don't start linking back from domain B etc to A,C,D,E,F,G trying to create a fake link popularity with your own domains. Two years ago would work on google, but not anymore.

Interesting... I would have to code some sort of hierarchy to have all the smaller domains link the bigger ones but not necessarily vice-versa.

Yes,that would be beneficial for you, you can still see once in a while such "spam sites" ranking high, but their life time is limited. The best reasearch tool you can use is the same google. If you do your own reasearch you'll get much more reliable answers from the ones you can find answered on boards and resources sites.

(I'm not with it today.) What do you mean by this? Do you mean the best research is to find out what sites are already ranked high and research them?

agree on that google is the best resource on SE investigation. However it's hard to tell what is the best tactics as it is very hard to tell apart short time spammers and long term profis. For example this guy is doing everything Soul_Rebel claims is bad (heavily interlinking, everything on one domain...) and is pretty high in listings and not for only few weeks:
http://www.penispictures.com/

So go figure ;)
XM

from what i see, this guy doesn't link/linkback to external domains. What he does is to link to several pages within his domain which is not prohibited from any SE.
Amazon.com for example has managed to get spidered some million pages this way, same with yahoo and many directories. I'm sure though that this internal linking is not the reason that his domain appears that high.